PURPOSE: To reduce fuel consumption by constituting logical circuit with air temperature sensor at down stream of evaporator, evaporator freezing sensor and engine load sensor and by restricting operation of refrigeration cycle under high load operation of the engine.

CONSTITUTION: Throttle opening sensor 21 which detects engine load and freezing sensor 20 which detects freezing of evaporator are connected to the AND- circuit 25 through an invertor 24; and this AND-circuit 25 and temperature sensor 19 which detects cabin temperature are connected to the OR-circuit 26 to form the control circuit 17A. This control circuit 17A operates the compressor 12 when the cabin temperature is higher than set-temperature, however, even when the temperature is low the compressor 12 is operated during the car load is medium or low to freeze the evaporator 3 and produce and store ice, which will be used for the cooling under high load engine operation.